[R] help pleaseeeeeeeee

[Steven McKinney]

Hi Clara,

I suspect your error is happening because your input data
is short (9 observations).  In the help for ar() for
argument "order.max" it states

order.max	 Maximum order (or order) of model to fit. Defaults to 10*log10(N) where N is the number of observations except for method="mle" where it is the minimum of this quantity and 12.

so perhaps the problem is 10*log10(9) is smaller than 1 and
isn't being handled properly (this is just a guess).

If I lengthen your data vector to be
x<-ts(c(-0.2052083,-0.3764986,-0.3762448,0.3740089,0.2737568,2.8235722,-1.7783313,0.2728676,-0.3273164,
  -0.2052083,-0.3764986,-0.3762448,0.3740089,0.2737568,2.8235722,-1.7783313,0.2728676,-0.3273164),start=c(1978,3),frequency=4,end=c(1982,3))

I can not trip the error.

I filed a bug report.

You might try specifying order.max in your
function call.  If I specify
order.max = 1
I can not trip the error.

> res.ar<-ar(x,aic=TRUE,demean=F)
> res.ar<-ar(x,aic=TRUE,demean=F)
Error in if (order > 0) coefs[order, 1:order] else numeric(0) : 
  missing value where TRUE/FALSE needed
In addition: Warning message:
In if (order > 0) coefs[order, 1:order] else numeric(0) :
  the condition has length > 1 and only the first element will be used
> res.ar<-ar(x,aic=TRUE,demean=F)
Error in if (order > 0) coefs[order, 1:order] else numeric(0) : 
  missing value where TRUE/FALSE needed
In addition: Warning message:
In if (order > 0) coefs[order, 1:order] else numeric(0) :
  the condition has length > 1 and only the first element will be used
> res.ar<-ar(x,aic=TRUE,demean=F, order.max = 1)
> res.ar<-ar(x,aic=TRUE,demean=F, order.max = 1)
> res.ar<-ar(x,aic=TRUE,demean=F, order.max = 1)
> res.ar<-ar(x,aic=TRUE,demean=F, order.max = 1)
> res.ar<-ar(x,aic=TRUE,demean=F, order.max = 1)
> res.ar<-ar(x,aic=TRUE,demean=F, order.max = 1)
> res.ar<-ar(x,aic=TRUE,demean=F, order.max = 1)
> res.ar<-ar(x,aic=TRUE,demean=F, order.max = 1)
> res.ar<-ar(x,aic=TRUE,demean=F, order.max = 1)
> res.ar<-ar(x,aic=TRUE,demean=F, order.max = 1)
> res.ar<-ar(x,aic=TRUE,demean=F, order.max = 1)
> res.ar<-ar(x,aic=TRUE,demean=F, order.max = 1)
> res.ar<-ar(x,aic=TRUE,demean=F, order.max = 1)
> res.ar<-ar(x,aic=TRUE,demean=F, order.max = 1)
> res.ar<-ar(x,aic=TRUE,demean=F, order.max = 1)
> res.ar<-ar(x,aic=TRUE,demean=F, order.max = 1)
> res.ar<-ar(x,aic=TRUE,demean=F, order.max = 1)
> res.ar<-ar(x,aic=TRUE,demean=F, order.max = 1)
> res.ar<-ar(x,aic=TRUE,demean=F, order.max = 1)
> res.ar<-ar(x,aic=TRUE,demean=F, order.max = 1)
> res.ar<-ar(x,aic=TRUE,demean=F, order.max = 1)
> res.ar<-ar(x,aic=TRUE,demean=F, order.max = 1)
> res.ar<-ar(x,aic=TRUE,demean=F, order.max = 1)
> res.ar<-ar(x,aic=TRUE,demean=F, order.max = 1)
> res.ar<-ar(x,aic=TRUE,demean=F, order.max = 1)
> res.ar<-ar(x,aic=TRUE,demean=F, order.max = 1)
> res.ar<-ar(x,aic=TRUE,demean=F, order.max = 1)
> res.ar<-ar(x,aic=TRUE,demean=F, order.max = 1)
> res.ar<-ar(x,aic=TRUE,demean=F, order.max = 1)
> res.ar<-ar(x,aic=TRUE,demean=F, order.max = 1)
> res.ar<-ar(x,aic=TRUE,demean=F, order.max = 1)
> res.ar<-ar(x,aic=TRUE,demean=F, order.max = 1)
> res.ar<-ar(x,aic=TRUE,demean=F, order.max = 1)
> res.ar<-ar(x,aic=TRUE,demean=F, order.max = 1)
> res.ar<-ar(x,aic=TRUE,demean=F, order.max = 1)
> res.ar<-ar(x,aic=TRUE,demean=F, order.max = 1)
> res.ar<-ar(x,aic=TRUE,demean=F, order.max = 1)
> res.ar<-ar(x,aic=TRUE,demean=F, order.max = 1)
> res.ar<-ar(x,aic=TRUE,demean=F, order.max = 1)
> res.ar<-ar(x,aic=TRUE,demean=F, order.max = 1)


> sessionInfo()
R version 2.6.0 (2007-10-03) 
powerpc-apple-darwin8.10.1 

locale:
en_CA.UTF-8/en_CA.UTF-8/en_CA.UTF-8/C/en_CA.UTF-8/en_CA.UTF-8

attached base packages:
[1] splines   stats     graphics  grDevices utils     datasets  methods   base     

other attached packages:
[1] survival_2.34

loaded via a namespace (and not attached):
[1] tools_2.6.0
> 


Steven McKinney

Statistician
Molecular Oncology and Breast Cancer Program
British Columbia Cancer Research Centre

email: smckinney +at+ bccrc +dot+ ca

tel: 604-675-8000 x7561

BCCRC
Molecular Oncology
675 West 10th Ave, Floor 4
Vancouver B.C. 
V5Z 1L3
Canada




-----Original Message-----
From: r-help-bounces at r-project.org on behalf of Clara Cordeiro
Sent: Fri 11/23/2007 7:38 AM
To: r-help at stat.math.ethz.ch
Subject: [R] help pleaseeeeeeeee
 
Dears Sirs

During my computational work I encountered unexpected behavior when calling
"ar" function, namely
# time series
x<-ts(c(-0.2052083,-0.3764986,-0.3762448,0.3740089,0.2737568,2.8235722,-
1.7783313,0.2728676,-0.3273164),start=c(1978,3),frequency=4,end=c(1980,3))

# ar function
res.ar<-ar(x,aic=TRUE,demean=F)

# call "ar" again and ............
res.ar<-ar(x,aic=TRUE,demean=F)
Error in if (order > 0) coefs[order, 1:order] else numeric(0) :
  missing value where TRUE/FALSE needed
In addition: Warning messages:
1: In log(var.pred) : NaNs produced
2: In if (order > 0) coefs[order, 1:order] else numeric(0) :
  the condition has length > 1 and only the first element will be used

For me it is mysterious why sometimes it works and others it does not,
perhaps I am doing something wrong and stupid :-(

If anyone had already had this problem could you please tell me how you have
solved it?

Thank you for your time.

Best Regards,

Clara Cordeiro

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